Coating apparatus



Nov. 21, 1944. J. FLAWS JR COATING APPARATUS Original Filed Jan. 14, 1942 Invervtor John Haws JT.

HIS AiTlTOTTEH.

w M a a H E Z M f f r f I \nlv\ g z z l 3 M F M Patented Nov. 21, 1944 COATING APP ARATUS John Flaws, Jr., East Cleveland, Ohio, assignor to General Electric Com New York pany, a corporation of Original application January 14, 1942, Serial No. 426,766. Divided and this application May 29, 1943, Serial No. 488,955

6 Claims. (01. 91-46) My invention relates to apparatus for coating filaments for electric lamps .or similar devices. This application is a division of my application Serial No. 426,766, filed January 14, 1942.

One of the objects of my invention is to provide apparatus which will apply a liquid coating to a definite portionof a coiled filament. More particularly, itis an object of my invention to provide apparatus which will apply a coating material to a coiled filament which is secured at its ends to portions of lead-in wires of a lamp mount, without applying the coating material to the joints between the said leadin wires and the ends of the filament or to any portion of the lead-in wires.

Further objects and advantages of my invenwith the filament ll lowermost, in a suitable holder which may comprise jaws ll which grip tion will appear from the following description of a species thereof and from the drawing.

In the drawing, Fig. 1 is a perspective view of a lamp mount carrying a filament or cath- "ode which is to be coated; Fig. 2 is an elevation, partly in section, of coating apparatus comprising my invention; Fig. 3 is a section, along line 3-3 of Fig.2, showing adipper or applicator portion of the apparatus; and Fig. 4 is a detailed sectional view of a trough portion of the applicator. i

Fig. 1 illustrates one form of mount carrying afilament which is coated by the apparatus comprising my invention. This mount is of the type disclosed and claimed in my Patent No. 2,312,245, dated February 23-, 1943, and it comprises a flare or stem tube 10, an exhaust tube ll, andleads I 2 which extend through theseal joining the said stem and exhaust tubes. The said seal is provided with an opening (not shown) between the leads l2 providing a passage through the stem from the exhaust tube. The inner ends of the leads l2 are bent outward, and intermediate portions thereof are bent to form oppositely facing hooks l3 in which are clamped the ends of a coiled-coil tungsten filament l4. ities I 5 of the said inner ends of the leads l2 are bent to extend parallel to and on opposite sides of the filament l4.

Themount just described is used in gaseous electric discharge lamps, such as the well-known fluorescent lamps. wherein two such mounts are sealed to opposite ends of a tubular envelope. The filament It then serves as a cathode, and the lead extremities l5 as auxiliary anodes. For this purposethe filament H is coated with an electromemissive material, indicated by the dotted lines l6.

Referring to Fig. 2, the mount I0 is supported,

The extremthe. exhaust tube ll. The said jaws Il may form part of a head which is moved along on a suitable carrier or turret, as shownin my parent application Serial No. 426,766, the coating apparatus being located at one of the stations into which the said head is indexed.

The coating apparatus comprises a cylindrical reservoir or cup "(having a conical bottom and containing the'liquidfcoating material l9. In this case, the coating material may consist of a suspension of powdered alkaline earth carbonates in a cellulose binder, and it is car; ried up to the filament H by a cup-shaped applicator or dipper member 20which is normally submerged in theliquid IS. The reservoir I8 is supported at its lower end by a post 2| which is held by a bracket 22 which may be mounted on a suitable table (not shown). The dipper 20 is carried by a vertical shaft 23, through an arm 24 androd 25, and is vertically reciprocated by said shaft 23 to thus agitate the liquid'lfl as well as to carry the applicator up to the filament It. The said shaft 23 is feciprocated by suitable mechanism which may include'suitable cam means (not shown) through the rod 26 and arm 21 which move the shaft 23 vertically in the bracket 22. The rod 25 is located in front of the vertical plane along whichcup IB is sectioned in Fig. 2 so that the said rod 25 and arm 24 clear the flare l0 when they move upward.

As shown in Fig. 2, and in Fig. 3 on a larger scale, the dipper 20 has .an opening 28 in the bottom thereof which permits the liquid l9 to circulate freely through it for an interval during which the dipper is repeatedly agitated up and down in the container l8, and the said opening also allows the liquid to drain back into the container l8 when the dipper is raised into operative relation to the filament l4. Both oper ations contribute'to thorough agitation of the liquid and complete replacement of the liquid within the dipper 2B and thetrough 29 in the upper edge of the partition or rib 30 within the said dipper. The said trough 29 is carried up about the filament H by movement of the dipper the interstices of the coiled-coil filament by capillary attraction. The center portion of the partition 30 which forms the trough 28 has a length such that it limits the application of the liquid to the portion of the filament ll between the lead wire hooks l3, thereby preventing the liquid from collecting on the leads and immediately adjacent portions of the filament. The coating on the filament is indicated at IS in Fig. l.

Various means are provided for controlling the thickness of the coating 18. The most important ofthese are the size and shape of the trough 29, the period of time the filament H is kept in said trough, and the viscosity of the coating liquid l9. In certain instances a second, and even a third coating may be applied to the filament ll. In an automatic machine such as disclosed in my parent application Serial No. 426,766, the said second and third coatings may be appliedby providing coating devices like the one disclosed herein at succeeding indexing stations of the machine.

Provision is made, by means of a bottle 3| and connecting passage 32, for replenishing the liquid is as rapidly as it is used. A spring clip 33 and bracket 34 hold the bottle Si in place.

What I claim as new and desire to secure by Letters Patent f the United States is:

1. In a device of the class described, means for supporting a stem having a, pair of leads thereon with a filament extending horizontally between said leads and attached thereto, and means for applying a liquid coating material to said filament comprising a horizontal trough-shaped member containing the coating material and located below said stem supporting means so that the longitudinal axes of the trough and filament are parallel and in alignment, said member hav-" ing a length shorter than the distance between the .points'of attachment of said filament to said leads, and means for effecting a relative move-' ment of said trough-shaped member and filament toward each other so that said filament enters the trough.

2. In a device of the class described, means for supporting a stem having a pair of leads thereon with a filament extending horizontally between said leads and attached thereto, a reservoir located below said supporting means and containing liquid coating material, a horizontal trough-shaped member normally submerged in the coating material in saidreservoir and disposed so that its longitudinal axis is parallel to and in alignment with the longitudinal axis of the filament, said trough-shaped member having a length shorter than the distance between the points of attachment of said filament to said leads and having is ends open, and means for moving said trough-shaped member upward out of the coating material in said reservoir and around said filament before the coating material drains out of the trough.

3. In a device of the class described, means for supporting .9, stem having a pair of leads thereonwith a filament extending horizontally between s'aid leads and attached thereto, a reservoir located below aid supporting means and containing liquid coating material, a cup-shaped dipper normally submerged in the coating material in said reservoir, a horizontal trough-shaped member carried by said dipper with its longitudinal axis parallel to and in alignment with the longitudinal axis of said filament, said troughshaped member having a length shorter than the distance between the points of attachment of said filament to said leads and having its ends open, and means for moving said dipper upward to-oarry said trough-shaped member out of the coating material and around said filament before the coating material drains out of the trough.

4. In a device of the class described, meansfor supporting a stem having a pair of leads thereon with a filament extending horizontally between said leads-and attached thereto, a reservoir located below said supporting means and containing liquid coating material, a cup-shaped dipper normally submerged in the coating material in said reservoir and having an opening in the bottom thereof, a horizontal trough-shaped member carried by said dipper with its longitudinal axis parallel to and in alignment with the longitudinal axis 'of aid filament, said trough-- shaped member having a length shorter than the distance between the points of attachment of said filament to said leads and having its ends open, and means for moving said dipper upward to carry said trough-shaped member out of the coating material and around said filament before the coating material drains out through the trough.

5. In a device of the class described, means for supporting astem having a pair of leads thereon with a filament extending horizontally be-' tween said leads and attached thereto, Hemvoir located below said supporting means and containing ilquid coating material, a cup-shaped dipper normally submerged in the coating material in said reservoir, a vertically extending partition in said dipper having a horizontal trough in its upper edge with its longitudinal axis parallel to and in alignment with the longitudinal axis J of said filament and of shorter length than the distance between the points of attachment of said filament to said leads, and means for moving said dipper upward to carry said trough out of the coating material and around said filament before the coating material drains out of the trough.

6. In apparatus of the class described for coating a filament, a reservoir for liquid coating material, an applicator member having a horizontally extending open-ended trough in its upper surface normally disposed in said reservoir with the trough submerged in the coating material, support means above said reservoir for supporting a filament in a horizontal-position with its longitudinal axis parallel to and in alignment with the longitudinal axis of the trough, and means for moving said applicator member upward out of the coating material toapp1y coating material in the trough to thefilament before the coating material drains out of the trough.

JOHN FLAWS, J11; 

